A dental kiln or oven having a display is known in the art, for example the Ivoclar Vivadent Programat® X1. With this kiln, various parameters are indicated on a display. This is intended to ensure that the operator of such a kiln selects the correct burning or firing curve. The display may optically compare how the combustion chamber temperature and the temperature of the object that is to be burned or fired differ from one another. Also to be provided is a desired value/actual value comparison.
When a patient visits a dentist for a new crown, the dentist makes an impression from the teeth and defines the colors of the tooth to be restored, or of the adjacent teeth, (e.g. A2, B3, . . . ) with the help of a color key, one such color key being shown in U.S. Pat. No. 5,653,589. Afterwards, the dental technician will receive the impression and a number of a color (e.g. A2) the new crown should have. After he has produced a fitting crown-cap, he has to build up this cap with fluent ceramic material whose material number agrees with the color number he received from the dentist. In a following production step the ceramic material has to be fired in a dental kiln.
If the dental technician works together with a good dentist, he will probably get two colors for the ceramic material, one color defining the incisal area of the tooth and a second color defining the color of the tooth adjacent the gum. What the dental technician doesn't have with this information is the exact run of the border between color one and color two. Therefore there might always be the risk that the new dental restoration doesn't exactly agree with the color of the tooth to be restored, although the technician has used the right ceramic colors.
It has furthermore become known to establish the desired tooth color via specialized computer-enhanced measures, and to transmit appropriate image data to the dental technician. For this purpose, it has been proposed, via a camera, to photograph existing teeth, with the photograph then being used for making available the prescribed tooth colors. One example of such an approach can be found in the shade analyzer shown in U.S. Pat. No. 6,786,726.
With the help of a shade analyzer the dentist makes a photo from the tooth to be restored or one of the neighboring teeth which corresponds at best with the color of the tooth to be restored. Then the photographed tooth will be subdivided in different regions positioned one upon the other beginning from the incisal area to the gum. For each of the different regions an average color and a number of the average color will be determined through a comparison with different colors stored in a control device of the shade analyzer. Then the data will be sent to the dental technician in the form of a picture (e.g., a .jpg file) and information concerning the color numbers of the regions in the form of one or more electronic files.
With such approaches, the tooth colors are established according to perception and visual comparison by the dental technician or the dentist, and appropriate specifications are prescribed for the selection of the tooth colors having the appropriate color codes (also, for example, A2, C1 or the like). The tooth is then divided into appropriate surface areas, and corresponding tooth colors are used during the restoration.
The dental technician then has the pertaining surface areas in front of him or her in a printed form or in some other suitable form during the manufacture of the tooth, and is then expected to prepare the corresponding tooth.
Despite this aid, the results of the restoration are frequently not satisfactory. For example, there can also be misunderstandings or incorrect interpretations with regard to the coding of the pertaining surface areas, especially if the pertaining tooth colors are written down by the dentist in longhand. In addition, a black and white expression makes it very difficult to assess the optical effect of the tooth that is to be restored, so that to this extent one must rely very heavily upon the experience not only of the dentist but also of the dental technician, which of course affects the result of the restoration.
There is also the danger that mistakes or mix-ups can occur, especially if, for example, a number of teeth are to be produced for the same patient, which teeth generally exhibit very little difference in shading.
Whereas fluctuations in color and slight errors can be tolerated in the molar region, the front teeth should have a particularly aesthetic appearance.